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// Copyright 2018 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"context"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"net"
"net/http"
"os"
"strconv"
"strings"
"time"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/prometheus/common/model"
"gopkg.in/alecthomas/kingpin.v2"
"github.com/prometheus/prometheus/discovery/targetgroup"
"github.com/prometheus/prometheus/documentation/examples/custom-sd/adapter"
"github.com/prometheus/prometheus/util/strutil"
)
var (
a = kingpin.New("sd adapter usage", "Tool to generate file_sd target files for unimplemented SD mechanisms.")
outputFile = a.Flag("output.file", "Output file for file_sd compatible file.").Default("custom_sd.json").String()
listenAddress = a.Flag("listen.address", "The address the Consul HTTP API is listening on for requests.").Default("localhost:8500").String()
logger log.Logger
// addressLabel is the name for the label containing a target's address.
addressLabel = model.MetaLabelPrefix + "consul_address"
// nodeLabel is the name for the label containing a target's node name.
nodeLabel = model.MetaLabelPrefix + "consul_node"
// tagsLabel is the name of the label containing the tags assigned to the target.
tagsLabel = model.MetaLabelPrefix + "consul_tags"
// serviceAddressLabel is the name of the label containing the (optional) service address.
serviceAddressLabel = model.MetaLabelPrefix + "consul_service_address"
//servicePortLabel is the name of the label containing the service port.
servicePortLabel = model.MetaLabelPrefix + "consul_service_port"
// serviceIDLabel is the name of the label containing the service ID.
serviceIDLabel = model.MetaLabelPrefix + "consul_service_id"
)
// CatalogService is copied from https://github.com/hashicorp/consul/blob/master/api/catalog.go
// this struct represents the response from a /service/<service-name> request.
// Consul License: https://github.com/hashicorp/consul/blob/master/LICENSE
type CatalogService struct {
ID string
Node string
Address string
Datacenter string
TaggedAddresses map[string]string
NodeMeta map[string]string
ServiceID string
ServiceName string
ServiceAddress string
ServiceTags []string
ServicePort int
ServiceEnableTagOverride bool
CreateIndex uint64
ModifyIndex uint64
}
// Note: create a config struct for your custom SD type here.
type sdConfig struct {
Address string
TagSeparator string
RefreshInterval int
}
// Note: This is the struct with your implementation of the Discoverer interface (see Run function).
// Discovery retrieves target information from a Consul server and updates them via watches.
type discovery struct {
address string
refreshInterval int
tagSeparator string
logger log.Logger
oldSourceList map[string]bool
}
func (d *discovery) parseServiceNodes(resp *http.Response, name string) (*targetgroup.Group, error) {
var nodes []*CatalogService
tgroup := targetgroup.Group{
Source: name,
Labels: make(model.LabelSet),
}
defer func() {
io.Copy(ioutil.Discard, resp.Body)
resp.Body.Close()
}()
b, err := ioutil.ReadAll(resp.Body)
if err != nil {
return nil, err
}
err = json.Unmarshal(b, &nodes)
if err != nil {
return &tgroup, err
}
tgroup.Targets = make([]model.LabelSet, 0, len(nodes))
for _, node := range nodes {
// We surround the separated list with the separator as well. This way regular expressions
// in relabeling rules don't have to consider tag positions.
var tags = "," + strings.Join(node.ServiceTags, ",") + ","
// If the service address is not empty it should be used instead of the node address
// since the service may be registered remotely through a different node.
var addr string
if node.ServiceAddress != "" {
addr = net.JoinHostPort(node.ServiceAddress, fmt.Sprintf("%d", node.ServicePort))
} else {
addr = net.JoinHostPort(node.Address, fmt.Sprintf("%d", node.ServicePort))
}
target := model.LabelSet{model.AddressLabel: model.LabelValue(addr)}
labels := model.LabelSet{
model.AddressLabel: model.LabelValue(addr),
model.LabelName(addressLabel): model.LabelValue(node.Address),
model.LabelName(nodeLabel): model.LabelValue(node.Node),
model.LabelName(tagsLabel): model.LabelValue(tags),
model.LabelName(serviceAddressLabel): model.LabelValue(node.ServiceAddress),
model.LabelName(servicePortLabel): model.LabelValue(strconv.Itoa(node.ServicePort)),
model.LabelName(serviceIDLabel): model.LabelValue(node.ServiceID),
}
tgroup.Labels = labels
// Add all key/value pairs from the node's metadata as their own labels.
for k, v := range node.NodeMeta {
name := strutil.SanitizeLabelName(k)
tgroup.Labels[model.LabelName(model.MetaLabelPrefix+name)] = model.LabelValue(v)
}
tgroup.Targets = append(tgroup.Targets, target)
}
return &tgroup, nil
}
// Note: you must implement this function for your discovery implementation as part of the
// Discoverer interface. Here you should query your SD for it's list of known targets, determine
// which of those targets you care about (for example, which of Consuls known services do you want
// to scrape for metrics), and then send those targets as a target.TargetGroup to the ch channel.
func (d *discovery) Run(ctx context.Context, ch chan<- []*targetgroup.Group) {
for c := time.Tick(time.Duration(d.refreshInterval) * time.Second); ; {
var srvs map[string][]string
resp, err := http.Get(fmt.Sprintf("http://%s/v1/catalog/services", d.address))
if err != nil {
level.Error(d.logger).Log("msg", "Error getting services list", "err", err)
time.Sleep(time.Duration(d.refreshInterval) * time.Second)
continue
}
b, err := ioutil.ReadAll(resp.Body)
io.Copy(ioutil.Discard, resp.Body)
resp.Body.Close()
if err != nil {
level.Error(d.logger).Log("msg", "Error reading services list", "err", err)
time.Sleep(time.Duration(d.refreshInterval) * time.Second)
continue
}
err = json.Unmarshal(b, &srvs)
resp.Body.Close()
if err != nil {
level.Error(d.logger).Log("msg", "Error parsing services list", "err", err)
time.Sleep(time.Duration(d.refreshInterval) * time.Second)
continue
}
var tgs []*targetgroup.Group
// Note that we treat errors when querying specific consul services as fatal for this
// iteration of the time.Tick loop. It's better to have some stale targets than an incomplete
// list of targets simply because there may have been a timeout. If the service is actually
// gone as far as consul is concerned, that will be picked up during the next iteration of
// the outer loop.
newSourceList := make(map[string]bool)
for name := range srvs {
if name == "consul" {
continue
}
resp, err := http.Get(fmt.Sprintf("http://%s/v1/catalog/service/%s", d.address, name))
if err != nil {
level.Error(d.logger).Log("msg", "Error getting services nodes", "service", name, "err", err)
break
}
tg, err := d.parseServiceNodes(resp, name)
if err != nil {
level.Error(d.logger).Log("msg", "Error parsing services nodes", "service", name, "err", err)
break
}
tgs = append(tgs, tg)
newSourceList[tg.Source] = true
}
// When targetGroup disappear, send an update with empty targetList.
for key := range d.oldSourceList {
if !newSourceList[key] {
tgs = append(tgs, &targetgroup.Group{
Source: key,
})
}
}
d.oldSourceList = newSourceList
if err == nil {
// We're returning all Consul services as a single targetgroup.
ch <- tgs
}
// Wait for ticker or exit when ctx is closed.
select {
case <-c:
continue
case <-ctx.Done():
return
}
}
}
func newDiscovery(conf sdConfig) (*discovery, error) {
cd := &discovery{
address: conf.Address,
refreshInterval: conf.RefreshInterval,
tagSeparator: conf.TagSeparator,
logger: logger,
oldSourceList: make(map[string]bool),
}
return cd, nil
}
func main() {
a.HelpFlag.Short('h')
_, err := a.Parse(os.Args[1:])
if err != nil {
fmt.Println("err: ", err)
return
}
logger = log.NewSyncLogger(log.NewLogfmtLogger(os.Stdout))
logger = log.With(logger, "ts", log.DefaultTimestampUTC, "caller", log.DefaultCaller)
ctx := context.Background()
// NOTE: create an instance of your new SD implementation here.
cfg := sdConfig{
TagSeparator: ",",
Address: *listenAddress,
RefreshInterval: 30,
}
disc, err := newDiscovery(cfg)
if err != nil {
fmt.Println("err: ", err)
}
sdAdapter := adapter.NewAdapter(ctx, *outputFile, "exampleSD", disc, logger)
sdAdapter.Run()
<-ctx.Done()
}